It is known in tank warfare to employ mine clearing apparatus mounted on a vehicle for clearing a path through a mine field.
There is described in U.S. Pat. Nos. 4,491,053, 4,467,694, 4,552,053, 4,590,844 and 4,727,940 mine clearing apparatus mountable on a tracked vehicle and which includes a pair of plow members mounted in front of the vehicle tracks.
U.S. Pat. No. 4,840,105 describes an element for exploding magnetic mines comprising a permanent magnet arranged for driven engagement with a ground surface, so as to provide rotation of the permanent magnet. The permanent magnet is disposed at a distance in front of a vehicle to be protected from mines, rotation of the permanent magnet providing premature detonation of mines in the vicinity thereof at a safe distance in front of the vehicle.
Magnetic mines include trigger mechanisms which are operative to detect changes in a range of predetermined intensities and in a range of predetermined frequencies in the surrounding magnetic field. The predetermined intensities and frequencies are selected to be similar to those that would be produced by travel of a heavy vehicle, such as a main battle tank. For any specific vehicle, the local changes to the surrounding magnetic field constitute the `magnetic signature` of that vehicle.
Different types of magnetic mine trigger mechanism are operative to respond to different types of magnetic signature. While the element described in U.S. Pat. No. 4,840,105 is effective in causing detonation of magnetic mines, a given element such as described cannot be used for simultaneous detonation of several types of magnetic mine of different manufacture, when the trigger mechanism of each different type of mine is responsive to a magnetic signature outside of that provided by the described element.
U.S. Pat. No. 4,951,571 entitled "Drum Minesweeper" describes a floating minesweeper for neutralizing marine mines. The minesweeper employs, inter alia, a plurality of permanent magnets for neutralizing magnetic marine mines, and is thus subject to a limitation similar to that of the element described in the above-summarized U.S. Pat. No. 4,840,105.
U.S. Pat. No. 4,938,136, entitled "Resonant Acousticmagnetic Minesweeper", is a towed minesweeper which is adapted to be towed in a suitable marine or land environment. The minesweeper employs an acoustic-magnetic generator for producing acoustic energy and magnetic energy which, when directed at an appropriate type of mine, causes self-destruction thereof. Magnetized pipes are employed for production of magnetic energy. The magnetized pipes are also effected by the acoustic energy produced by the generator so as to vibrate and thus cause varying or alternating magnetic fields. Varying or alternating magnetic fields are also stated as being given to being produced by means of solenoid coils powered by an ac current source.
The use of a simple ac current source for directly powering solenoid coils provides a magnetic field which varies through a fixed cycle. While such a system may, therefore, be effective in causing detonation of magnetic mines, per se, it cannot provide simultaneous detonation of several types of magnetic mine of different manufacture, when the trigger mechanism of each different type of mine is responsive to a magnetic signature outside of that provided by the described system.